For the past few years telecommunications systems have been evolving, apparently ineluctably, toward data transfer in compliance with the Internet Protocol (IP), in particular because the Internet Protocol offers the interactivity that is lacking in conventional broadcasting systems.
This trend affected terrestrial networks first, but is now extending to networks based on satellite infrastructures.
To meet this new requirement, satellite networks must therefore face up to new technical problems.
Solutions have already been proposed for transporting IP data packets in a satellite network but since those solutions are often the result of adapting systems initially dedicated to transporting point-to-point voice traffic or broadcast video traffic, they employ protocols that have not been optimized.
Traditionally, a satellite telecommunications system offers broadcast services, i.e. one-way data transmission, from a sender to a set of recipients and circuit mode call services, i.e. calls from one given point to another given point based on a virtual “circuit” or “cable” set up temporarily between the two points for calls between them.
In the world of the Internet, services providing calls between one user and another user registered with the same Internet service provider require two dedicated circuits to be set up, one from each user to the common Internet service provider, so that connection of the one user to the other user via the satellite system generates a double hop, i.e. double use of the satellite. This multiple hop phenomenon is accentuated if the two users are not registered with the same Internet service provider, as further hops are then necessary to interconnect the Internet service providers.
The same problem arises when sending data to a particular group of users, whether by means of a broadcast service, which is often referred to as a “multi-recipient” or “multicast” service (as opposed to a broadcast service aimed at all users of the system), or by means of a call in a virtual private sub-network that groups together certain users. For multi-recipient or virtual sub-network broadcasting, packets intended for a plurality of users are duplicated to as many recipients, and the data travels over as many dedicated traffic channels, or circuits, which unnecessarily increases the load on the network.
Another imperative that has to be considered is that it must be possible to integrate satellite networks offering facilities for transactions in accordance with the Internet Protocol transparently into terrestrial networks so that users can reach all Internet addresses on the world wide web, to send as well as to receive data, without concerning themselves about the path taken by the data packets to provide the transmission, and can thereby benefit from all Internet services already available on terrestrial networks.